From: high.crew3868@fastmail.com   
      
   On 1/1/26 11:26 PM, Michael S wrote:   
   > On Thu, 1 Jan 2026 22:54:05 +0100   
   > highcrew  wrote:   
   >> For the lazy, I report it here:   
   >>   
   >>     int table[4] = {0};   
   >>     int exists_in_table(int v)   
   >>     {   
   >>         // return true in one of the first 4 iterations   
   >>         // or UB due to out-of-bounds access   
   >>         for (int i = 0; i <= 4; i++) {   
   >>             if (table[i] == v) return 1;   
   >>         }   
   >>         return 0;   
   >>     }   
   >>   
   >> This is compiled (with no warning whatsoever) into:   
   >>   
   >>     exists_in_table:   
   >>             mov     eax, 1   
   >>             ret   
   >>     table:   
   >>             .zero   16   
   >>   
    > [...]   
    >   
   > IMHO, for compiler that eliminated all comparisons (I assume that it was   
   > gcc -O2/-O3) an absence of warning is a bug.   
      
   Correct: -O2.  Same code compiled with -O0:   
   https://godbolt.org/z/xE61j3PdM -> Still no warnings, although it will   
   at least contain   
   the `return 0`.   
      
   Which doesn't mean it is better: the code is obviously wrong, and   
   *I think* the compiler should whine.   
      
    > It's worth reporting.   
      
   Do you think so? I think everybody already knows...   
      
   First off, this example is mentioned since forever on the cppreference   
   website.  Secondly, no warning is issued by Clang either.   
      
   Again, with this I don't mean the compilers are behaving correctly.   
   I just think this situation is well known.   
      
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   High Crew   
      
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